The shaykh mentions this point of benefit in the beginning of his explanation of “Qawaaidul Arba’ah”:

“This is a very important matter! Knowledge of (Tawheed and Shirk) is more incumbent upon you than the rulings of: siyaam (fasting), salaah (prayer), zakah (obligatory alms), etc. It is the foremost matter and foundation because, salaah, zakah, hajj, and other acts of ibaadaat are not correct if it is not built upon the foundation of correct aqeedah, and that is to have tawheed sincerely for Allaah azza wa Jal.”